U.S. patent application number 16/415247 was filed with the patent office on 2020-11-19 for vehicle suspension system.
This patent application is currently assigned to KUBOTA CORPORATION. The applicant listed for this patent is KUBOTA CORPORATION. Invention is credited to Eric CHANG, John WHITE.
Application Number | 20200361409 16/415247 |
Document ID | / |
Family ID | 1000004124114 |
Filed Date | 2020-11-19 |
United States Patent
Application |
20200361409 |
Kind Code |
A1 |
CHANG; Eric ; et
al. |
November 19, 2020 |
VEHICLE SUSPENSION SYSTEM
Abstract
A vehicle suspension system includes suspension arms mounted to
a vehicle body frame to be pivotable between a low rolling posture
and a high rolling posture and an anti-roll bar unit. The anti-roll
bar unit includes a main anti-roll bar and a sub anti-roll bar. The
sub anti-roll bar extends at least partially parallel with the main
anti-roll bar. In the low rolling posture of the suspension arms,
the main anti-roll bar and the sub anti-roll bar are not in contact
with each other. In the high rolling posture of the suspension
bars, the main anti-roll bar and the sub anti-roll bar are in
contact with each other to increase stiffness of the anti-roll bar
unit.
Inventors: |
CHANG; Eric; (Buford,
GA) ; WHITE; John; (Gainesville, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KUBOTA CORPORATION |
Osaka |
|
JP |
|
|
Assignee: |
KUBOTA CORPORATION
Osaka
JP
|
Family ID: |
1000004124114 |
Appl. No.: |
16/415247 |
Filed: |
May 17, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60G 21/0551 20130101;
B60G 2200/144 20130101; B60G 2204/1224 20130101 |
International
Class: |
B60R 21/13 20060101
B60R021/13; B60G 7/00 20060101 B60G007/00; B60G 21/055 20060101
B60G021/055 |
Claims
1. A vehicle suspension system comprising: left and right
suspension arms mounted to a vehicle body frame to be pivotable
between a low rolling posture and a high rolling posture; and an
anti-roll bar unit that bridges the left suspension arm with the
right suspension arm, the anti-roll bar unit including: a main
anti-roll bar having a left end operably attached to the left
suspension arm and a right end operably attached to the right
suspension arm; and a sub anti-roll bar extending at least
partially parallel with the main anti-roll bar; wherein in the low
rolling posture, the main anti-roll bar and the sub anti-roll bar
are not in contact with each other; and in the high rolling
posture, the main anti-roll bar and the sub anti-roll bar are in
contact with each other to increase stiffness of the anti-roll bar
unit.
2. The vehicle suspension system of claim 1, wherein the main
anti-roll bar and the sub anti-roll bar are pivotally supported to
the vehicle body frame.
3. The vehicle suspension system of claim 1, wherein: the main
anti-roll bar includes a main bar body which extends straight in
the vehicle body transverse direction, a left main arm which is
bent from the left end of the main bar body and extends rearwards
in the vehicle body front/rear direction, a right main arm which is
bent from the right end of the main bar body and extends rearwards
in the vehicle body front/rear direction, a left link having one
end connected to the left main arm and the other end connected to
the left suspension arm and a right link having one end connected
to the right main arm and the other end connected to the right
suspension arm; and the sub anti-roll bar includes a sub bar body
extending straight in the vehicle body transverse direction, a left
sub arm which is bent from the left end of the sub bar body and
extends rearwards in the vehicle body front/rear direction and a
right sub bar arm which is bent from the right end of the sub bar
body and extends rearwards in the vehicle body front/rear
direction.
4. The vehicle suspension system of claim 3, wherein: the leading
end region of the left sub arm is formed as a left ring through
which the left main arm extends, an inner circumferential wall of
the left ring coming into contact with the left main arm in the
high rolling posture; and the leading end region of the right sub
arm is formed as a right ring through which the right main arm
extends, an inner circumferential wall of the right ring coming
into contact with the right main arm in the high rolling
posture.
5. The vehicle suspension system of claim 4, wherein the inner
circumferential walls of the left ring and the right ring
respectively come into contact with the left main arm and the right
main arm via an elastic member.
6. The vehicle suspension system of claim 3, wherein the main bar
body and the sub bar body respectively are attached to the vehicle
body frame via a bush.
Description
TECHNICAL FIELD
[0001] This invention relates to a vehicle suspension system having
an anti-roll bar.
BACKGROUND ART
[0002] In the case of an independent suspension in which a left
wheel and a right wheel are suspended independently, in the course
of traveling at a corner, an acceleration in the lateral direction
affecting the vehicle body causes a stroke difference between the
left wheel and the right wheel, which causes rolling of the vehicle
body. In order to reduce such vehicle body rolling, an anti-roll
bar functioning as a torsion spring having U-shape in a plan view
interconnects a left suspension arm with a right suspension arm.
For instance, U.S. Pat. No. 7,322,591 discloses a vehicle
suspension in which a left suspension arm and a right suspension
arm are interconnected via an anti-roll bar. A torsion spring
constant is determined in consideration to a torsional moment which
increases with increase of the stroke difference between the
wheels. The torsional stiffness which is determined by the torsion
spring constant of this anti-roll bar affects riding feel and
handling performance. However, since the torsion spring constant is
a characteristic value determined by shape and material of the
anti-roll bar, it is difficult for a single anti-roll bar to
provide a torsional stiffness which is appropriate over the entire
range of stroke difference between the left wheel and the right
wheel.
[0003] This problem can be effectively solved by an active
suspension system configured to dynamically change the
characteristics of the suspension via an electronic control.
However, this system requires a costly sensor and actuator as well
as a controller therefor. Therefore, this system is complicated in
its configuration and costly in its manufacture and maintenance
costs.
SUMMARY OF THE INVENTION
[0004] An object of the present invention is to provide a vehicle
suspension system having an anti-roll bar with an appropriate
torsional stiffness though a simple configuration.
[0005] A vehicle suspension system according to the present
invention includes left and right suspension arms mounted to a
vehicle body frame to be pivotable between a low rolling posture
and a high rolling posture and an anti-roll bar unit that bridges
the left suspension arm with the right suspension arm. The
anti-roll bar unit includes a main anti-roll bar and a sub
anti-roll bar. The main anti-roll bar has a left end operably
attached to the left suspension arm and a right end operably
attached to the right suspension arm. The sub anti-roll bar extends
at least partially parallel with the main anti-roll bar. In the low
rolling posture, the main anti-roll bar and the sub anti-roll bar
are not in contact with each other; and in the high rolling
posture, the main anti-roll bar and the sub anti-roll bar are in
contact with each other to increase stiffness of the anti-roll bar
unit.
[0006] Incidentally, the low rolling posture includes a neutral
state (neutral posture) in which strokes of the left and right
suspension arms are equal to each other. Namely, the low rolling
posture refers to a vehicle posture in which strokes of the left
and right suspension arms are equal to each other or only slightly
different from each other. In this, a rolling angle of the vehicle
body is zero or below a predetermined angle. Whereas, the high
rolling posture refers to a vehicle posture in which the rolling
angle of the vehicle body exceeds the predetermined rolling
angle.
[0007] The anti-roll bar unit employed in this invention comprises
a double anti-roll bar, having a main anti-roll bar and a sub
anti-roll bar. The main anti-roll bar functions as a torsion spring
in both the low rolling posture and the high rolling posture of the
left and right suspension arms, namely, in the entire range of
stroke difference between the left and right suspension arms. In
contrast, the sub anti-roll bar can "float" relative to the left
and right suspension arms in the low rolling posture of the left
and right suspension arms. This sub anti-roll bar functions as a
torsion spring only in the high rolling posture.
[0008] In a normal traveling condition, the left and right
suspension arms will be kept under the low rolling posture, so this
antiroll bar unit ensures a comfortable riding feel and good
handling performance provided by the conventional suspension
comprised of a single anti-roll bar. Further, in a severe traveling
condition such as sharp cornering, this anti-roll bar unit
functions as a strong torsion spring through the combination of the
main antiroll bar and the sub anti-roll bar, thus ensuring
stability under such severe traveling condition also. The inventive
vehicle suspension system employing such double anti-roll ar can
provide superior riding feel and handling performance in both a
normal traveling condition and a severe traveling condition, in
spite of its simple arrangement.
[0009] Preferably, the main anti-roll bar and the sub anti-roll bar
come into contact with each other via an elastic member such as a
rubber isolator, in order to reduce noise and/or vibration caused
when the main anti-roll bar and the sub anti-roll bar come into
contact and become combined with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of a multi-purpose vehicle,
[0011] FIG. 2 is a plan view of the multi-purpose vehicle,
[0012] FIG. 3 is a perspective view showing a vehicle body frame
and a vehicle suspension system,
[0013] FIG. 4 is a perspective view showing the vehicle suspension
system,
[0014] FIG. 5 is a perspective view of an anti-roll bar unit,
[0015] FIG. 6 is a side view of the anti-roll bar unit, and
[0016] FIG. 7 is a front view of the anti-roll bar unit.
DETAILED DESCRIPTION
[0017] Next, an embodiment of a vehicle suspension system according
to the present invention will be explained. In this embodiment, the
vehicle suspension system is applied to a multi-purpose vehicle
(utility vehicle). Incidentally, in this detailed description,
unless indicated otherwise, a word "front" means the front
(forward) side with respect to a vehicle body front/rear direction
(traveling direction). A word "rear" means the rear (rearward or
reverse) side with respect to the vehicle body front/rear direction
(traveling direction). Further, a language "left/right direction"
or "lateral direction" means a vehicle body transverse direction
(vehicle body width direction) perpendicular to the vehicle body
front/rear direction. Also, a word "upper" and a word "lower"
respectively refer to positional relationship in the perpendicular
direction (vertical direction) of the vehicle body, indicating
relationship in terms of ground clearance height.
[0018] FIG. 1 is a side view of the multi-purpose vehicle. FIG. 2
is a plan view of the multi-purpose vehicle. Such multi-purpose
vehicle is a vehicle for use in a variety of purposes such as
transportation of load, a recreational activity, etc. This
multi-purpose vehicle includes a pair of left and right front
wheels 1 that can be steered and driven, a pair of left and right
rear wheels 2 that can be driven and a vehicle body frame 3. On the
vehicle body frame 3, there are provided a driving chamber DR in
which a driver (operator) will ride, a load deck 4 capable of
mounting a load, and an engine 11 located under the load deck 4. At
a front portion of the vehicle body frame 3, there is provided a
hood 5 which can be opened/closed.
[0019] Though shown only schematically in FIG. 1 and FIG. 2, there
are provided a front suspension device FS for independently
suspending the left and right front wheels 1 from the vehicle body
frame 3 and a rear suspension device RS for independently
suspending the left and right rear wheels 2 from the vehicle body
frame 3. The front suspension device FS and the rear suspension
device RS are double wishbone suspensions.
[0020] As shown in FIG. 2, power of the engine 11 is speed-changed
steplessly through a stepless speed changer device 12 and then
transmitted to a rear transmission 13. This rear transmission 13
includes a gear type speed changer mechanism providing forward
traveling states (a forward first speed state and a forward second
speed state), a reverse traveling stage and a neutral state. Power
from the rear transmission is transmitted to a rear axle 14 and
then transmitted from this rear axle 14 to the left and right rear
wheels 2. Further, the power from the rear transmission 13 is
transmitted via a PTO (power takeoff) shaft 15, a propelling shaft
16 and a front transmission 17 to a front axle 18. The front axle
18 is connected with the left and right front wheels 1.
[0021] FIG. 3 shows the front suspension device FS mounted at a
front portion of the vehicle body frame 3. FIG. 4 shows the front
suspension device FS only. A left upper suspension arm 51L and a
left lower suspension arm 52L together constituting the left
suspension arm are attached to a front left portion of the vehicle
body frame 3 via a bracket 31 to be pivotable up/down. A right
upper suspension arm 51R and a right lower suspension arm 52R
together constituting the right suspension arm are attached to a
front right portion of the vehicle body frame 3 via a bracket 31 to
be pivotable up/down. Free ends of the left upper suspension arm
51L and the left lower suspension arm 52L are connected to the left
front wheel 1 via a knuckle arm unit 30. Free ends of the right
upper suspension arm 51R and the right lower suspension arm 52R are
connected to the right front wheel 1 via a knuckle arm unit 30.
[0022] Between and across the left upper suspension arm 51L and the
vehicle body 3, a left cushion unit 53L is provided. Between and
across the right upper suspension arm 51R and the vehicle body 3, a
right cushion unit 53R is provided. The left cushion unit 53L and
the right cushion unit 53R respectively is comprised of a coil
spring and a damper unit. When an acceleration in the lateral
direction is applied to the vehicle body in the course of e.g. a
cornering, there will develop a difference between the stroke of
the left cushion unit 53L (the stroke of the left suspension arm)
and the stroke of the right cushion unit 53R (the stroke of the
right suspension arm). Due to this stroke difference, the vehicle
body will roll. Here, a posture in which the vehicle body rolls
within a predetermined rolling angle is referred to a low rolling
posture and a posture in which the vehicle body rolls at an angle
exceeding the predetermined rolling angle is referred to as a high
rolling posture. The vehicle posture in which the rolling angle of
the vehicle body is substantially zero is referred to as a neutral
posture in particular.
[0023] In order to suppress such rolling of the vehicle body due to
a stroke difference between the stroke of the left suspension arm
and the stroke of the right suspension arm, there is provided an
antiroll bar unit 6 which bridges the left suspension arm with the
right suspension arm. This anti-roll bar unit 6, as shown in FIG.
5, includes a main anti-roll bar 61 and a sub anti-roll bar 62.
[0024] The main anti-roll bar 61 has an approximately C-shape as
seen in a plan view and includes a main bar body 610 which extends
straight in the vehicle body transverse direction, a left main arm
611 which is bent from the left end of the main bar body 610 and
extends rearwards in the vehicle body front/rear direction, and a
right main arm 612 which is bent from the right end of the main bar
body 610 and extends rearwards in the vehicle body front/rear
direction. The right main arm 612 is connected to the vehicle body
frame 3 via a right link 63. For the connection between the left
link 63 and the right main bar 612 and the connection between the
right link 64 and the vehicle body frame 3, ball joints or pin
joints are employed. The main bar body 610, the left main arm 611
and the right main arm 612 are formed by bending of a single round
bar.
[0025] The sub anti-roll bar 62 has an approximately U-shape as
seen in a plan view and includes a sub bar body 620 extending
straight in the vehicle body transverse direction, a left sub arm
621 which is bent from the left end of the sub bar body 620 and
extends rearwards in the vehicle body front/rear direction and a
right sub bar arm 622 which is bent from the right end of the sub
bar body 620 and extends rearwards in the vehicle body front/rear
direction.
[0026] The leading end region of the left sub arm 621 is formed as
a left ring 623. Similarly, the leading end region of the right sub
arm 622 is formed as a right ring 624. The left ring 623 and the
right ring 624 are formed to follow a plane perpendicular to the
vehicle body front/rear direction line. The sub bar body 620, the
left sub arm 621 and the right sub arm 622 are formed by bending a
single round bar.
[0027] As shown in FIG. 5, FIG. 6 and FIG. 7, the main anti-roll
bar 61 and the sub anti-roll bar 62 are assembled in such a manner
that the main bar body 610 and the sub bar body 620 extend
substantially parallel with each other, in which the left main arm
611 extends through the opening formed by the left ring 623 and the
right main arm 612 extends through the opening formed by the right
ring 624.
[0028] As shown in FIG. 3, the main bar body 610 and the sub bar
body 620 are supported via two bushes 66 fixed to the vehicle body
frame 3 with using brackets and spaced apart from each other to be
torsionably rotatable.
[0029] The main anti-roll bar 61 and the sub anti-roll bar 62 are
supported to the vehicle body frame 3 via bushes 66. However, the
opposed ends of the sub anti-roll bar 62 are kept free, whereas the
opposed ends of the main anti-roll bar 61 are fixed to the vehicle
body frame 3 via the left link 63 and the right link 64. Therefore,
when the strokes of the left and right suspensions differ from each
other, there will occur a relative positional displacement between
the main anti-roll bar 61 and the sub anti-roll bar 62.
[0030] When the posture (vehicle posture) of the suspension device
is the neutral posture (in which the rolling angle is substantially
zero), the left main arm 611 of the main anti-roll bar 61 will be
located substantially at the center of the opening of the left ring
623 of the sub anti-roll bar 62. Similarly, the right main arm 612
of the main anti-roll bar 61 will be located substantially at the
center of the opening of the right ring 624 of the sub anti-roll
bar 61.
[0031] When the posture (vehicle posture) of the suspension device
is the low rolling posture (the rolling angle is within the
predetermined rolling angle), the left main arm 611 is located
within the opening of the left ring 623, not in contact therewith.
Similarly, the right main arm 612 is located within the opening of
the right ring 624, not in contact therewith.
[0032] When the posture (vehicle posture) of the suspension device
is the high rolling posture (the rolling angle exceeds the
predetermined rolling angle), the left main arm 611 will come into
contact with the inner circumferential wall of the left ring 623
and the right main arm 621 will come into contact with the inner
circumferential wall of the right ring 624, thus combining the main
anti-roll bar 61 with the sub anti-roll bar 62. With this, a
torsional moment applied to the main anti-roll bar 61 will be
received by the main anti-roll bar 61 and the sub anti-roll bar 62.
Namely, the stiffness of the anti-roll bar unit 6 will be increased
thereby.
[0033] In order to reduce noise and/or vibration at the time of
contact between the left main arm 611 and the inner circumferential
wall of the left ring 623, a sleeve-like rubber-formed isolator 65
is engaged on the left main arm 611. Similarly, in order to reduce
noise and/or vibration at the time of contact between the right
main arm 612 and the inner circumferential wall of the right ring
624, a sleeve-like rubber-formed isolator 65 is engaged on the
right main arm 612. Incidentally, instead of the above-described
arrangements, the rubber-formed isolators 65 can be provided in the
left ring 623 and the right ring 624, respectively.
[0034] In the meantime, the arrangements disclosed in the foregoing
embodiment (including the further embodiment) can be used in
combination with arrangements disclosed in the other embodiments as
long as such combination does not result in contradiction. Further,
it is understood that the embodiments disclosed in this detailed
disclosure are only illustrative, and the scope of the present
invention is not limited thereto. In fact, various modifications
can be made appropriately within a range not deviating from the
essence of the invention.
* * * * *